654 FXUS63 KDVN 291930 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 230 PM CDT Mon Jun 29 2026 .KEY MESSAGES... - Extreme Heat Warning continues through Wednesday evening due to a prolonged period of hot and very humid conditions. Daily peak heat index values of 100 to 110 and nighttime low temperatures only dropping into the mid 70s. - Increasing thunderstorm chances into midweek onward (including the July 4th weekend), with the resultant cloud cover potentially having an impact on high temperatures. Very humid conditions will remain. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 230 PM CDT Mon Jun 29 2026 Upper ridge to continue across the central and southeastern US with southwesterly flow across the Plains into the Great Lakes. This pattern continues to allow the heat to build across the area with very humid conditions as well with flow off the Gulf. Heat index values already into 100-105 range or higher at many sites today, and even warmer air aloft expected to push into the area Tuesday. Little relief expected at night with the humid airmass and warm temperatures keeping overnight temperatures dropping into the upper 70s to around 80. The Extreme Heat Warning will continue with the heat expected through midweek. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Issued at 230 PM CDT Mon Jun 29 2026 The upper ridge across the central/southern US to begin to break down some into the middle to end of the week allowing the southwesterly flow aloft to become oriented more across the forecast area. This will bring increasing chances for thunderstorms by Wednesday into the weekend, especially into the weekend as the ridge breaks down further with a more zonal flow pattern setting up with stronger shortwave troughs impacting the region. Therefore the continuation of the heat and high temperatures into the end of the week and this weekend are somewhat uncertain dependent on thunderstorm chances due to cloud cover and overall storm chances, etc. Continued moisture flow off the Gulf remains, so humid conditions will continue through the forecast period. For now the threat of strong to severe storms is still uncertain for any one period, however the pattern would suggest more organization with the storm chances into the weekend with the stronger upper level troughs helping force the storm chances. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 117 PM CDT Mon Jun 29 2026 Winds and some low level CU the main issues in the terminal forecasts today. Gusty southerly winds today, should begin to diminish some overnight with the gustiness before picking up again into Tuesday. MVFR CU expected to lift to lower VFR this afternoon, with skies clearing overnight, potentially some very high thin cirrus. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Extreme Heat Warning until 10 PM CDT Wednesday for IAZ040>042- 051>054-063>068-076>078-087>089-098-099. IL...Extreme Heat Warning until 10 PM CDT Wednesday for ILZ001-002- 007-009-015>018-024>026-034-035. MO...Extreme Heat Warning until 10 PM CDT Wednesday for MOZ009-010. && $$ SHORT TERM...MJB LONG TERM...MJB AVIATION...MJB